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Debbie wants to take a foot or two off the top. Should she?

In this week's Gardening Tips, Susan Richards answers that question and more, including one about a pergola

Each week, Susan Richards of New North Greenhouses answers your gardening questions. Have questions about your gardening needs? Please email her at

Debbie: We have a large cedar hedge that is approximately 14 feet tall which we are finding more difficult to trim each year.  We would like to keep the hedge, however wonder if it is ok to have it trimmed down by 1 to 2 feet off the top so it could be easier to maintain?

You can certainly trim down the hedge but it will look much better if you do it in a slow and careful way.

If you were to just take a hedge trimmer and cut off 2 feet at the tip, your entire hedge will look very ugly at the top. Instead look at the main stem of each plant and go in to the middle to cut off the desired length. Leave all the side branches untrimmed at this point.

Then stand back and look at what growth you have left. Carefully trim the side shoots back ensuring that there is some new growth left on each stem. This method of pruning will allow the top to fill in nicely.

G Bruni: I have a pergola in a sunny location and would like something to plant so when it grows it will cover it for shade. What do you recommend.

Grapes and hardy kiwi are ideal to grow on a pergola in full sun and you have the added bonus of fruit! Just be sure to choose a hardy grape variety and if using kiwi, plant at least one male plant to pollinate the females.

If you aren't interested in fruit, you can look at a few other options:

Virginia creeper is a fast growing vine that turns a brilliant red in fall. Honeysuckle vine has beautiful flowers.

Carol: When is the best time to prune a Royal Purple Smoke Bush? I can never seem to get that misty look.

All smoke bushes should be pruned in early spring when dormant. If you missed that time and the new growth has begun, still prune right now. Then don't prune again this season. The 'misty' flower clusters are produced on the ends of the new growth in late summer.

If you were pruning midsummer, that would be why you didn't see the 'smoke'. Hopefully you have the shrub planted in enough sun. they need full sun or at least all afternoon sun to really thrive.

Alison: What is the best soil mix for growing vegetables in containers?

Be sure to use a good quality potting soil mixed with compost for your vegetable pot. I use an organic potting soil mixed in this way" 2/3 potting soil with 1/3 compost.

Never use garden soil in your containers. It's too heavy for the pots, not allowing adequate aeration or drainage. You also run the risk if introducing insects and disease into your pots.

Don't use peat moss as a container soil. It's too acidic. Although most potting soils are peat moss based, they have lime added to neutralize the acidity of the peat moss.